So far, four taxi tests of 15-20 minutes each have been completed. These were just slowly around the parking area and runup bay, getting a feel for the plane. I’ve also calibrated the magnetometer so the ADAHRS has stopped showing error messages.

I have been at the front of the hangar for a change so able to get the plane out. The weather doesn’t matter for these tests.

The last test was with the cowls on. When the engine starts I get a general coolant pump warning, low coolant pressure warning, low pressure from the oil and so on. This tends to inoculate a person to these messages and given I’m not above 1300rpm I pretty much ignored them.  The pump warning did go off and come on again so I turned on the backup water pump just to be sure.

When I stopped the engine back at the hangar there was a LOT of coolant on the ground. It turns out I’d blown a Welsh plug! This was the one we replaced that was leaking from when the engine was delivered. Clearly the installation technique needs improvement.

Of course I was not going to get of lightly. This failure in the air would mean I’d have to shut down the engine or wait for it to seize. On the ground it meant the engine just got hot… but the coolant temps were constant as there was nothing to show the sensors with no water present. I didn’t know. Given the water pressure is zero at start-up with a warning, then it slowly climbs towards 15psi. I missed any message that it must have dropped from that.

So the engine got hot and the cowls hot enough to blister the paint both top and bottom. <sigh> At some point these cowls will need a complete repaint. You can see the marks above like a case of the hives. Review of the engine logs showed nothing catastrophic so I really got of lightly if you consider the big picture.

These glorified bottle tops are cheap but losing an engine isn’t.

I googled how to put them in, I watched five videos and each one had its own method. After a bit I understood what to do rather than follow the instructions like a robot. Every single person also had a favourite sealant too. The more I looked, the more options were presented.

I went for the anaerobic sealant I have used on the water system sensors. This has worked well where others have leaked, so more of the same seems a good thing to try.   The important part seems to be getting the plug in via the edges and not touching the middle. The wedging holds the plug in under pressure, not the sealant.

With that sorted out, the next day I drained the coolant which was only about 2 litres despite the sight tube level indicator showing full!  I filled again with the 50:50 fresh green stuff by pulling a vacuum at the cap this gives me a much better chance of having no air pockets in the liquid.

What to do about these CAS messages that are false on start-up? It turns out that with recent software changes to the G3X you can make messages ‘conditional’. We have set things up so many of these messages happen after the engine has been started and running for a bit. This should make them appear when they are REAL warnings, not false ones so I’ll take more notice.

We also reconfigured the fuel level system to now display on the G3X rather than the AG6 annunciator button that I had spent a huge amount of time and money on. When taxi testing it seems stuck on low sump despite there being 60 litres of fuel in the plane. It’s just been a PIA to program and hook up.  With software updates to the Garmin G3X it can now  accept different voltage levels for fuel annunciations.

Here’s the AG6 button which is currently disconnected and dark. I’m thinking maybe it could be a Master warning for all the major CAS annunciations but I’m reluctant to go to my long suffering avionics guy right at the moment!

Next up is getting the exhaust pipes tweaked again so the sit in the middle of the cowl openings. This is a cut and shut procedure. Then its back to the engine fuel tuning issues which are not yet resolved. I also have to stiffen the top cowl. I’ll do a separate blog entry on all that. Its a bit of work.